We present a micro-macro strategy able to describe the dynamics of crowds in
heterogeneous media. Herein we focus on the example of pedestrian counterflow.
The main working tools include the use of mass and porosity measures together
with their transport as well as suitable application of a version of
Radon-Nikodym Theorem formulated for finite measures. Finally, we illustrate
numerically our microscopic model and emphasize the effects produced by an
implicitly defined social velocity.
Keywords: Crowd dynamics; mass measures; porosity measure; social network